Contact recording tunnel magnetoresistive sensor with layer of refractory metal

ABSTRACT

Various embodiments relate to an apparatus having a sensor with an active tunnel magnetoresistive region, magnetic shields flanking the tunnel magnetoresistive region, and gaps between the active tunnel magnetoresistive region and the magnetic shields. The active tunnel magnetoresistive region includes a free layer, a tunnel barrier layer and a reference layer. At least one of the gaps includes an electrically conductive layer having a refractory material. Other embodiments relate to an apparatus having a sensor with an active tunnel magnetoresistive region, magnetic shields flanking the tunnel magnetoresistive region, and gaps between the tunnel magnetoresistive region and the magnetic shields. The active tunnel magnetoresistive region includes a free layer, a tunnel barrier layer and a reference layer. At least one of the gaps includes an electrically conductive layer having a modified region at a media facing side thereof, the modified region being at least one of nonconductive and mechanically hardened.

BACKGROUND

The present invention relates to data storage systems, and moreparticularly, this invention relates to tunnel magnetoresistive (TMR)sensors implemented in contact recording.

In magnetic storage systems, magnetic transducers read data from andwrite data onto magnetic recording media. Data is written on themagnetic recording media by moving a magnetic recording transducer to aposition over the media where the data is to be stored. The magneticrecording transducer then generates a magnetic field, which encodes thedata into the magnetic media. Data is read from the media by similarlypositioning the magnetic read transducer and then sensing the magneticfield of the magnetic media. Read and write operations may beindependently synchronized with the movement of the media to ensure thatthe data can be read from and written to the desired location on themedia.

An important and continuing goal in the data storage industry is that ofincreasing the density of data stored on a medium. For tape storagesystems, that goal has led to increasing the track and linear bitdensity on recording tape, and decreasing the thickness of the magnetictape medium. However, the development of small footprint, higherperformance tape drive systems has created various problems in thedesign of a tape head assembly for use in such systems.

In a tape drive system, the drive moves the magnetic tape over thesurface of the tape head at high speed. Usually the tape head isdesigned to minimize the spacing between the head and the tape. Thespacing between the magnetic head and the magnetic tape is crucial andso goals in these systems are to have the recording gaps of thetransducers, which are the source of the magnetic recording flux in nearcontact with the tape to effect writing sharp transitions, and to havethe read elements in near contact with the tape to provide effectivecoupling of the magnetic field from the tape to the read elements.

Minimization of the spacing between the head and the tape, however,induces frequent contact between the tape and the media facing side ofthe head, causing tape operations to be deemed a type of “contactrecording.” This contact, in view of the high tape speeds and tapeabrasivity, quickly affects the integrity of the materials used to formthe media facing surface of the head, e.g., causing wear thereto,smearing which is known to cause shorts, etc.

BRIEF SUMMARY

Various embodiments relate to an apparatus having a sensor with anactive tunnel magnetoresistive region, magnetic shields flanking thetunnel magnetoresistive region, and gaps between the active tunnelmagnetoresistive region and the magnetic shields. The active tunnelmagnetoresistive region includes a free layer, a tunnel barrier layerand a reference layer. At least one of the gaps includes an electricallyconductive layer having a refractory material.

Other embodiments relate to an apparatus having a sensor with an activetunnel magnetoresistive region, magnetic shields flanking the tunnelmagnetoresistive region, and gaps between the tunnel magnetoresistiveregion and the magnetic shields. The active tunnel magnetoresistiveregion includes a free layer, a tunnel barrier layer and a referencelayer. At least one of the gaps includes an electrically conductivelayer having a modified region at a media facing side thereof, themodified region being at least one of nonconductive and mechanicallyhardened.

Any of these embodiments may be implemented in a magnetic data storagesystem such as a tape drive system, which may include a magnetic head, adrive mechanism for passing a magnetic medium (e.g., recording tape)over the magnetic head, and a controller electrically coupled to themagnetic head.

Other aspects and embodiments of the present invention will becomeapparent from the following detailed description, which, when taken inconjunction with the drawings, illustrate by way of example theprinciples of the invention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1A is a schematic diagram of a simplified tape drive systemaccording to one embodiment.

FIG. 1B is a schematic diagram of a tape cartridge according to oneembodiment.

FIG. 2 illustrates a side view of a flat-lapped, bi-directional,two-module magnetic tape head according to one embodiment.

FIG. 2A is a tape bearing surface view taken from Line 2A of FIG. 2.

FIG. 2B is a detailed view taken from Circle 2B of FIG. 2A.

FIG. 2C is a detailed view of a partial tape bearing surface of a pairof modules.

FIG. 3 is a partial tape bearing surface view of a magnetic head havinga write-read-write configuration.

FIG. 4 is a partial tape bearing surface view of a magnetic head havinga read-write-read configuration.

FIG. 5 is a side view of a magnetic tape head with three modulesaccording to one embodiment where the modules all generally lie alongabout parallel planes.

FIG. 6 is a side view of a magnetic tape head with three modules in atangent (angled) configuration.

FIG. 7 is a side view of a magnetic tape head with three modules in anoverwrap configuration.

FIG. 8A is a partial media facing side view of a sensor stack, accordingto one embodiment.

FIG. 8B is a partial cross-sectional view taken from Line 8B-8B of FIG.8A.

FIG. 9 is a partial side view of a sensor stack, according to oneembodiment.

FIG. 10 is a partial side view of a sensor stack, according to oneembodiment.

DETAILED DESCRIPTION

The following description is made for the purpose of illustrating thegeneral principles of the present invention and is not meant to limitthe inventive concepts claimed herein. Further, particular featuresdescribed herein can be used in combination with other describedfeatures in each of the various possible combinations and permutations.

Unless otherwise specifically defined herein, all terms are to be giventheir broadest possible interpretation including meanings implied fromthe specification as well as meanings understood by those skilled in theart and/or as defined in dictionaries, treatises, etc.

It must also be noted that, as used in the specification and theappended claims, the singular forms “a,” “an” and “the” include pluralreferents unless otherwise specified.

The following description discloses several preferred embodiments ofmagnetic storage systems, as well as operation and/or component partsthereof.

In one general embodiment, an apparatus has a sensor with an activetunnel magnetoresistive region, magnetic shields flanking the tunnelmagnetoresistive region, and gaps between the active tunnelmagnetoresistive region and the magnetic shields. The active tunnelmagnetoresistive region includes a free layer, a tunnel barrier layerand a reference layer. At least one of the gaps includes an electricallyconductive layer having a refractory material.

In another general embodiment, an apparatus has a sensor with an activetunnel magnetoresistive region, magnetic shields flanking the tunnelmagnetoresistive region, and gaps between the tunnel magnetoresistiveregion and the magnetic shields. The active tunnel magnetoresistiveregion includes a free layer, a tunnel barrier layer and a referencelayer. At least one of the gaps includes an electrically conductivelayer having a modified region at a media facing side thereof, themodified region being at least one of nonconductive and mechanicallyhardened.

FIG. 1A illustrates a simplified tape drive 100 of a tape-based datastorage system, which may be employed in the context of the presentinvention. While one specific implementation of a tape drive is shown inFIG. 1A, it should be noted that the embodiments described herein may beimplemented in the context of any type of tape drive system.

As shown, a tape supply cartridge 120 and a take-up reel 121 areprovided to support a tape 122. One or more of the reels may form partof a removable cartridge and are not necessarily part of the system 100.The tape drive, such as that illustrated in FIG. 1A, may further includedrive motor(s) to drive the tape supply cartridge 120 and the take-upreel 121 to move the tape 122 over a tape head 126 of any type. Suchhead may include an array of readers, writers, or both.

Guides 125 guide the tape 122 across the tape head 126. Such tape head126 is in turn coupled to a controller 128 via a cable 130. Thecontroller 128, may be or include a processor and/or any logic forcontrolling any subsystem of the drive 100. For example, the controller128 typically controls head functions such as servo following, datawriting, data reading, etc. The controller 128 may operate under logicknown in the art, as well as any logic disclosed herein. The controller128 may be coupled to a memory 136 of any known type, which may storeinstructions executable by the controller 128. Moreover, the controller128 may be configured and/or programmable to perform or control some orall of the methodology presented herein. Thus, the controller may beconsidered configured to perform various operations by way of logicprogrammed into a chip; software, firmware, or other instructions beingavailable to a processor; etc. and combinations thereof.

The cable 130 may include read/write circuits to transmit data to thehead 126 to be recorded on the tape 122 and to receive data read by thehead 126 from the tape 122. An actuator 132 controls position of thehead 126 relative to the tape 122.

An interface 134 may also be provided for communication between the tapedrive 100 and a host (integral or external) to send and receive the dataand for controlling the operation of the tape drive 100 andcommunicating the status of the tape drive 100 to the host, all as willbe understood by those of skill in the art.

FIG. 1B illustrates an exemplary tape cartridge 150 according to oneembodiment. Such tape cartridge 150 may be used with a system such asthat shown in FIG. 1A. As shown, the tape cartridge 150 includes ahousing 152, a tape 122 in the housing 152, and a nonvolatile memory 156coupled to the housing 152. In some embodiments, the nonvolatile memory156 may be embedded inside the housing 152, as shown in FIG. 1B. In moreembodiments, the nonvolatile memory 156 may be attached to the inside oroutside of the housing 152 without modification of the housing 152. Forexample, the nonvolatile memory may be embedded in a self-adhesive label154. In one preferred embodiment, the nonvolatile memory 156 may be aFlash memory device, ROM device, etc., embedded into or coupled to theinside or outside of the tape cartridge 150. The nonvolatile memory isaccessible by the tape drive and the tape operating software (the driversoftware), and/or other device.

By way of example, FIG. 2 illustrates a side view of a flat-lapped,bi-directional, two-module magnetic tape head 200 which may beimplemented in the context of the present invention. As shown, the headincludes a pair of bases 202, each equipped with a module 204, and fixedat a small angle α with respect to each other. The bases may be“U-beams” that are adhesively coupled together. Each module 204 includesa substrate 204A and a closure 204B with a thin film portion, commonlyreferred to as a “gap” in which the readers and/or writers 206 areformed. In use, a tape 208 is moved over the modules 204 along a media(tape) bearing surface 209 in the manner shown for reading and writingdata on the tape 208 using the readers and writers. The wrap angle θ ofthe tape 208 at edges going onto and exiting the flat media supportsurfaces 209 are usually between about 0.1 degree and about 3 degrees.

The substrates 204A are typically constructed of a wear resistantmaterial, such as a ceramic. The closures 204B made of the same orsimilar ceramic as the substrates 204A.

The readers and writers may be arranged in a piggyback or mergedconfiguration. An illustrative piggybacked configuration comprises a(magnetically inductive) writer transducer on top of (or below) a(magnetically shielded) reader transducer (e.g., a magnetoresistivereader, etc.), wherein the poles of the writer and the shields of thereader are generally separated. An illustrative merged configurationcomprises one reader shield in the same physical layer as one writerpole (hence, “merged”). The readers and writers may also be arranged inan interleaved configuration. Alternatively, each array of channels maybe readers or writers only. Any of these arrays may contain one or moreservo track readers for reading servo data on the medium.

FIG. 2A illustrates the tape bearing surface 209 of one of the modules204 taken from Line 2A of FIG. 2. A representative tape 208 is shown indashed lines. The module 204 is preferably long enough to be able tosupport the tape as the head steps between data bands.

In this example, the tape 208 includes 4 to 22 data bands, e.g., with 16data bands and 17 servo tracks 210, as shown in FIG. 2A on a one-halfinch wide tape 208. The data bands are defined between servo tracks 210.Each data band may include a number of data tracks, for example 1024data tracks (not shown). During read/write operations, the readersand/or writers 206 are positioned to specific track positions within oneof the data bands. Outer readers, sometimes called servo readers, readthe servo tracks 210. The servo signals are in turn used to keep thereaders and/or writers 206 aligned with a particular set of tracksduring the read/write operations.

FIG. 2B depicts a plurality of readers and/or writers 206 formed in agap 218 on the module 204 in Circle 2B of FIG. 2A. As shown, the arrayof readers and writers 206 includes, for example, 16 writers 214, 16readers 216 and two servo readers 212, though the number of elements mayvary. Illustrative embodiments include 8, 16, 32, 40, and 64 activereaders and/or writers 206 per array, and alternatively interleaveddesigns having odd numbers of reader or writers such as 17, 25, 33, etc.An illustrative embodiment includes 32 readers per array and/or 32writers per array, where the actual number of transducer elements couldbe greater, e.g., 33, 34, etc. This allows the tape to travel moreslowly, thereby reducing speed-induced tracking and mechanicaldifficulties and/or execute fewer “wraps” to fill or read the tape.While the readers and writers may be arranged in a piggybackconfiguration as shown in FIG. 2B, the readers 216 and writers 214 mayalso be arranged in an interleaved configuration. Alternatively, eacharray of readers and/or writers 206 may be readers or writers only, andthe arrays may contain one or more servo readers 212. As noted byconsidering FIGS. 2 and 2A-B together, each module 204 may include acomplementary set of readers and/or writers 206 for such things asbi-directional reading and writing, read-while-write capability,backward compatibility, etc.

FIG. 2C shows a partial tape bearing surface view of complimentarymodules of a magnetic tape head 200 according to one embodiment. In thisembodiment, each module has a plurality of read/write (R/W) pairs in apiggyback configuration formed on a common substrate 204A and anoptional electrically insulative layer 236. The writers, exemplified bythe write transducer 214 and the readers, exemplified by the readtransducer 216, are aligned parallel to an intended direction of travelof a tape medium thereacross to form an R/W pair, exemplified by the R/Wpair 222. Note that the intended direction of tape travel is sometimesreferred to herein as the direction of tape travel, and such terms maybe used interchangeable. Such direction of tape travel may be inferredfrom the design of the system, e.g., by examining the guides; observingthe actual direction of tape travel relative to the reference point;etc. Moreover, in a system operable for bi-direction reading and/orwriting, the direction of tape travel in both directions is typicallyparallel and thus both directions may be considered equivalent to eachother.

Several R/W pairs 222 may be present, such as 8, 16, 32 pairs, etc. TheR/W pairs 222 as shown are linearly aligned in a direction generallyperpendicular to a direction of tape travel thereacross. However, thepairs may also be aligned diagonally, etc. Servo readers 212 arepositioned on the outside of the array of R/W pairs, the function ofwhich is well known.

Generally, the magnetic tape medium moves in either a forward or reversedirection as indicated by arrow 220. The magnetic tape medium and headassembly 200 operate in a transducing relationship in the mannerwell-known in the art. The piggybacked MR head assembly 200 includes twothin-film modules 224 and 226 of generally identical construction.

Modules 224 and 226 are joined together with a space present betweenclosures 204B thereof (partially shown) to form a single physical unitto provide read-while-write capability by activating the writer of theleading module and reader of the trailing module aligned with the writerof the leading module parallel to the direction of tape travel relativethereto. When a module 224, 226 of a piggyback head 200 is constructed,layers are formed in the gap 218 created above an electricallyconductive substrate 204A (partially shown), e.g., of AlTiC, ingenerally the following order for the R/W pairs 222: an insulating layer236, a first shield 232 typically of an iron alloy such as NiFe (—), CZTor Al—Fe—Si (Sendust), a sensor 234 for sensing a data track on amagnetic medium, a second shield 238 typically of a nickel-iron alloy(e.g., ˜80/20 at % NiFe, also known as permalloy), first and secondwriter pole tips 228, 230, and a coil (not shown). The sensor may be ofany known type, including those based on MR, GMR, AMR, TMR, etc.

The first and second writer poles 228, 230 may be fabricated from highmagnetic moment materials such as ˜45/55 NiFe. Note that these materialsare provided by way of example only, and other materials may be used.Additional layers such as insulation between the shields and/or poletips and an insulation layer surrounding the sensor may be present.Illustrative materials for the insulation include alumina and otheroxides, insulative polymers, etc.

The configuration of the tape head 126 according to one embodimentincludes multiple modules, preferably three or more. In awrite-read-write (W-R-W) head, outer modules for writing flank one ormore inner modules for reading. Referring to FIG. 3, depicting a W-R-Wconfiguration, the outer modules 252, 256 each include one or morearrays of writers 260. The inner module 254 of FIG. 3 includes one ormore arrays of readers 258 in a similar configuration. Variations of amulti-module head include a R-W-R head (FIG. 4), a R-R-W head, a W-W-Rhead, etc. In yet other variations, one or more of the modules may haveread/write pairs of transducers. Moreover, more than three modules maybe present. In further embodiments, two outer modules may flank two ormore inner modules, e.g., in a W-R-R-W, a R-W-W-R arrangement, etc. Forsimplicity, a W-R-W head is used primarily herein to exemplifyembodiments of the present invention. One skilled in the art apprisedwith the teachings herein will appreciate how permutations of thepresent invention would apply to configurations other than a W-R-Wconfiguration.

FIG. 5 illustrates a magnetic head 126 according to one embodiment ofthe present invention that includes first, second and third modules 302,304, 306 each having a tape bearing surface 308, 310, 312 respectively,which may be flat, contoured, etc. Note that while the term “tapebearing surface” appears to imply that the surface facing the tape 315is in physical contact with the tape bearing surface, this is notnecessarily the case. Rather, only a portion of the tape may be incontact with the tape bearing surface, constantly or intermittently,with other portions of the tape riding (or “flying”) above the tapebearing surface on a layer of air, sometimes referred to as an “airbearing”. The first module 302 will be referred to as the “leading”module as it is the first module encountered by the tape in a threemodule design for tape moving in the indicated direction. The thirdmodule 306 will be referred to as the “trailing” module. The trailingmodule follows the middle module and is the last module seen by the tapein a three module design. The leading and trailing modules 302, 306 arereferred to collectively as outer modules. Also note that the outermodules 302, 306 will alternate as leading modules, depending on thedirection of travel of the tape 315.

In one embodiment, the tape bearing surfaces 308, 310, 312 of the first,second and third modules 302, 304, 306 lie on about parallel planes(which is meant to include parallel and nearly parallel planes, e.g.,between parallel and tangential as in FIG. 6), and the tape bearingsurface 310 of the second module 304 is above the tape bearing surfaces308, 312 of the first and third modules 302, 306. As described below,this has the effect of creating the desired wrap angle α₂ of the taperelative to the tape bearing surface 310 of the second module 304.

Where the tape bearing surfaces 308, 310, 312 lie along parallel ornearly parallel yet offset planes, intuitively, the tape should peel offof the tape bearing surface 308 of the leading module 302. However, thevacuum created by the skiving edge 318 of the leading module 302 hasbeen found by experimentation to be sufficient to keep the tape adheredto the tape bearing surface 308 of the leading module 302. The trailingedge 320 of the leading module 302 (the end from which the tape leavesthe leading module 302) is the approximate reference point which definesthe wrap angle α₂ over the tape bearing surface 310 of the second module304. The tape stays in close proximity to the tape bearing surface untilclose to the trailing edge 320 of the leading module 302. Accordingly,read and/or write elements 322 may be located near the trailing edges ofthe outer modules 302, 306. These embodiments are particularly adaptedfor write-read-write applications.

A benefit of this and other embodiments described herein is that,because the outer modules 302, 306 are fixed at a determined offset fromthe second module 304, the inner wrap angle α₂ is fixed when the modules302, 304, 306 are coupled together or are otherwise fixed into a head.The inner wrap angle α₂ is approximately tan⁻¹(δ/W) where δ is theheight difference between the planes of the tape bearing surfaces 308,310 and W is the width between the opposing ends of the tape bearingsurfaces 308, 310. An illustrative inner wrap angle α₂ is in a range ofabout 0.3° to about 1.1°, though can be any angle required by thedesign.

Beneficially, the inner wrap angle α₂ on the side of the module 304receiving the tape (leading edge) will be larger than the inner wrapangle α₃ on the trailing edge, as the tape 315 rides above the trailingmodule 306. This difference is generally beneficial as a smaller α₃tends to oppose what has heretofore been a steeper exiting effectivewrap angle.

Note that the tape bearing surfaces 308, 312 of the outer modules 302,306 are positioned to achieve a negative wrap angle at the trailing edge320 of the leading module 302. This is generally beneficial in helpingto reduce friction due to contact with the trailing edge 320, providedthat proper consideration is given to the location of the crowbar regionthat forms in the tape where it peels off the head. This negative wrapangle also reduces flutter and scrubbing damage to the elements on theleading module 302. Further, at the trailing module 306, the tape 315flies over the tape bearing surface 312 so there is virtually no wear onthe elements when tape is moving in this direction. Particularly, thetape 315 entrains air and so will not significantly ride on the tapebearing surface 312 of the third module 306 (some contact may occur).This is permissible, because the leading module 302 is writing while thetrailing module 306 is idle.

Writing and reading functions are performed by different modules at anygiven time. In one embodiment, the second module 304 includes aplurality of data and optional servo readers 331 and no writers. Thefirst and third modules 302, 306 include a plurality of writers 322 andno data readers, with the exception that the outer modules 302, 306 mayinclude optional servo readers. The servo readers may be used toposition the head during reading and/or writing operations. The servoreader(s) on each module are typically located towards the end of thearray of readers or writers.

By having only readers or side by side writers and servo readers in thegap between the substrate and closure, the gap length can besubstantially reduced. Typical heads have piggybacked readers andwriters, where the writer is formed above each reader. A typical gap is20-35 microns. However, irregularities on the tape may tend to droopinto the gap and create gap erosion. Thus, the smaller the gap is thebetter. The smaller gap enabled herein exhibits fewer wear relatedproblems.

In some embodiments, the second module 304 has a closure, while thefirst and third modules 302, 306 do not have a closure. Where there isno closure, preferably a hard coating is added to the module. Onepreferred coating is diamond-like carbon (DLC).

In the embodiment shown in FIG. 5, the first, second, and third modules302, 304, 306 each have a closure 332, 334, 336, which extends the tapebearing surface of the associated module, thereby effectivelypositioning the read/write elements away from the edge of the tapebearing surface. The closure 332 on the second module 304 can be aceramic closure of a type typically found on tape heads. The closures334, 336 of the first and third modules 302, 306, however, may beshorter than the closure 332 of the second module 304 as measuredparallel to a direction of tape travel over the respective module. Thisenables positioning the modules closer together. One way to produceshorter closures 334, 336 is to lap the standard ceramic closures of thesecond module 304 an additional amount. Another way is to plate ordeposit thin film closures above the elements during thin filmprocessing. For example, a thin film closure of a hard material such asSendust or nickel-iron alloy (e.g., 45/55) can be formed on the module.

With reduced-thickness ceramic or thin film closures 334, 336 or noclosures on the outer modules 302, 306, the write-to-read gap spacingcan be reduced to less than about 1 mm, e.g., about 0.75 mm, or 50% lessthan commonly-used LTO tape head spacing. The open space between themodules 302, 304, 306 can still be set to approximately 0.5 to 0.6 mm,which in some embodiments is ideal for stabilizing tape motion over thesecond module 304.

Depending on tape tension and stiffness, it may be desirable to anglethe tape bearing surfaces of the outer modules relative to the tapebearing surface of the second module. FIG. 6 illustrates an embodimentwhere the modules 302, 304, 306 are in a tangent or nearly tangent(angled) configuration. Particularly, the tape bearing surfaces of theouter modules 302, 306 are about parallel to the tape at the desiredwrap angle α₂ of the second module 304. In other words, the planes ofthe tape bearing surfaces 308, 312 of the outer modules 302, 306 areoriented at about the desired wrap angle α₂ of the tape 315 relative tothe second module 304. The tape will also pop off of the trailing module306 in this embodiment, thereby reducing wear on the elements in thetrailing module 306. These embodiments are particularly useful forwrite-read-write applications. Additional aspects of these embodimentsare similar to those given above.

Typically, the tape wrap angles may be set about midway between theembodiments shown in FIGS. 5 and 6.

FIG. 7 illustrates an embodiment where the modules 302, 304, 306 are inan overwrap configuration. Particularly, the tape bearing surfaces 308,312 of the outer modules 302, 306 are angled slightly more than the tape315 when set at the desired wrap angle α₂ relative to the second module304. In this embodiment, the tape does not pop off of the trailingmodule, allowing it to be used for writing or reading. Accordingly, theleading and middle modules can both perform reading and/or writingfunctions while the trailing module can read any just-written data.Thus, these embodiments are preferred for write-read-write,read-write-read, and write-write-read applications. In the latterembodiments, closures should be wider than the tape canopies forensuring read capability. The wider closures may require a widergap-to-gap separation. Therefore a preferred embodiment has awrite-read-write configuration, which may use shortened closures thatthus allow closer gap-to-gap separation.

Additional aspects of the embodiments shown in FIGS. 6 and 7 are similarto those given above.

A 32 channel version of a multi-module head 126 may use cables 350having leads on the same or smaller pitch as current 16 channelpiggyback LTO modules, or alternatively the connections on the modulemay be organ-keyboarded for a 50% reduction in cable span. Over-under,writing pair unshielded cables may be used for the writers, which mayhave integrated servo readers.

The outer wrap angles α₁ may be set in the drive, such as by guides ofany type known in the art, such as adjustable rollers, slides, etc. oralternatively by outriggers, which are integral to the head. Forexample, rollers having an offset axis may be used to set the wrapangles. The offset axis creates an orbital arc of rotation, allowingprecise alignment of the wrap angle α₁.

To assemble any of the embodiments described above, conventional u-beamassembly can be used. Accordingly, the mass of the resultant head may bemaintained or even reduced relative to heads of previous generations. Inother embodiments, the modules may be constructed as a unitary body.Those skilled in the art, armed with the present teachings, willappreciate that other known methods of manufacturing such heads may beadapted for use in constructing such heads.

Conventional TMR structures have been developed strictly for non-contactrecording, such as hard disk drive (HDD) recording. Because the head innon-contact recording flies above the medium, there is no need forrobustness. However, conventional TMR structures pose a serious problemwhen implemented in contact recording environments, such as taperecording environments. Namely, contact between the magnetic medium andthe sensor structure during contact recording may deform the sensorlayers and/or lead structures, effectively smearing the material of eachof these layers across the media facing side of the sensor structure,and thereby resulting in electrical shorting of the TMR device, whichimplements a parasitic current perpendicular to the plane (CPP)configuration. Once the device has been electrically shorted, it may berendered useless.

Moreover, during the lapping that is performed to define themedia-facing surface and establish the sensor stripe height, materialsmay smear, resulting in electrical shorts that significantly alter theperformance of the finished head.

Materials, such as nickel-chrome alloys, used in the non-magneticportion of the TMR sensor gap, have led to shorting. Various attempts toalleviate shorting in such conventional devices have resulted indiminished signal output thereby leading to reduced signal-to-noiseratio and/or resulted in otherwise non-optimal performance, ultimatelyleading to higher error rates, higher write skips and/or more frequentre-writes, loss of throughput and loss of capacity, all of which arehighly undesirable.

For current-in-plane (CIP) devices such as AMR and GMR sensors,pre-recession processing selectively etches the magnetic shields, thusfacilitating formation of protective insulating ‘walls’ that inhibitshorting due to tape-head contact. However, in CPP TMR sensors, thereare no insulating films in the sensor stack itself, apart from thetunnel barrier, to allow this coating methodology to work. Thus, whileeffective for AMR and GMR sensors, these methods may not adequatelyprotect against shorting for TMR sensors when implemented in contactrecording environments.

In sharp contrast, various embodiments described and/or suggested hereininclude TMR sensors having an improved media facing interface therebyresulting in a high resistance to electrical shorting of the sensorand/or its leads. According to some embodiments, this improved mediainterface may be achieved through wafer level solutions, while in otherembodiments, the improved media interface may result from a post wafersolution, as will be described in detail below.

Looking to FIGS. 8A-8B, an apparatus 800 is illustrated, in accordancewith one embodiment. As an option, the present apparatus 800 may beimplemented in conjunction with features from any other embodimentlisted herein, such as those described with reference to the other FIGS.Of course, however, such apparatus 800 and others presented herein maybe used in various applications and/or in permutations which may or maynot be specifically described in the illustrative embodiments listedherein. Further, the apparatus 800 presented herein may be used in anydesired environment. Thus FIGS. 8A-8B (and the other FIGS.) should bedeemed to include any and all possible permutations.

The apparatus 800 includes a sensor 802 having a media facing side 803,an active TMR region 804. The sensor 802 also includes magnetic shields806, 808 flanking (sandwiching) the TMR region 804, and electricallyconductive, non-magnetic gaps 810, 812 between the TMR region 804 andthe magnetic shields 806, 808. Except as otherwise described herein, thevarious components of the apparatus of FIGS. 8A-8B may be ofconventional materials and designs, as would be understood by oneskilled in the art.

The apparatus 800 may also include overcoat and undercoat layers 824,826, which may have any conventional construction, e.g., may include analumina material.

Furthermore, the active TMR region 804 includes a free layer 814, atunnel barrier layer 816 and a reference layer 818. According to variousembodiments, the free layer 814, the tunnel barrier layer 816 and/or thereference layer 818 may include construction parameters, e.g.,materials, dimensions, properties, etc., according to any of theembodiments described herein, and/or conventional constructionparameters, depending on the desired embodiment. Illustrative materialsfor the tunnel barrier layer 816 include amorphous and/or crystallineforms of, but are not limited to, TiOx, MgO and A₂O₃.

An insulating layer 832 may be interposed between hard bias layers 830and the active TMR region 804 to prevent parasitic current flow parallelto current flow through the sensor.

With continued reference to FIGS. 8A-8B, at least one of the gaps 810,812 preferably includes an electrically conductive layer, which containa refractory material. It should be noted that the gaps 810, 812 shownin the figures are representational, and do not depict the variouspotential layers therein that may cumulatively form the gaps 810, 812according to various embodiments. Thus, according to some embodiments,one or both of the gaps 810, 812 may include layers in addition to theelectrically conductive layer, including, but not limited to seed layers(e.g., Cr, Ta, etc.), nonmagnetic spacer layers, antiferromagneticlayers, etc. For example, a seed layer may be disposed between therefractory material and a surface underlying the refractory material.However, in other embodiments, the electrically conductive layer mayform the whole of one or both gaps 810, 812.

Illustrative materials for the refractory material include metals, e.g.,titanium-tungsten, tungsten carbide, rhodium, ruthenium, iridium, etc.,and/or alloys thereof. However in other embodiments, the refractorymaterial may include, but is not limited to, an electrically conductiveoxide, a conductive nitride, and/or a conductive carbide. Further still,according to an illustrative embodiment, the refractory material mayinclude a non-annealed sendust. Sendust composition is typically 85 at %iron, 9 at % silicon and 6 at % aluminum, but the ratios of thecomponents may vary from these general concentrations.

Depending on the desired embodiment, the electrically conductive layermay be formed using a single refractory material, however, in otherembodiments, the electrically conductive layer may have a layeredstructure. Thus, an electrically conductive layer may be formed from anumber of sublayers, each of which may include a different refractorymaterial according to any of those listed herein.

The layer of refractory material may be mechanically mismatched to theadjacent layers. For example, they may have different stress levels,which may affect adhesion. Accordingly, an adhesion layer may beemployed to promote adhesion of the layer of refractory material toanother layer in the structure. Conventional adhesion layers may beused. Examples include silicon nitride, Ta, Cr, Si, etc.

Another example of a mismatch could be related to the internal stress ofthe refractory material layer. The stress can be modified to some extentby controlling process conditions such as pressure, temperature, rate ofdeposition, etc. and/or inclusion of other materials that serve toreduce or otherwise alter the internal stress.

Furthermore, another consideration for the refractory material layerrelates to the surface roughness of the final film, especially for suchlayer under the active TMR region. A processing step may be performed toreduce surface roughness, such as chemical mechanical polishing (CMP),etching or other surface treatment. Alternatively, the processingconditions for the refractory material layer can be tailored to minimizeroughness. Controlling surface roughness of the lower refractorymaterial layer may be particularly important to maintain the integrityof the tunnel barrier layer.

Illustrative thicknesses for the gaps 810, 812 and/or layer ofrefractory material therein may be from 10-70 nm per film, but could behigher or lower.

FIG. 9 depicts an apparatus 900 that is a variation of the embodiment ofFIGS. 8A-8B, in accordance with one embodiment. As an option, thepresent apparatus 900 may be implemented in conjunction with featuresfrom any other embodiment listed herein, such as those described withreference to the other FIGS. Of course, however, such apparatus 900 andothers presented herein may be used in various applications and/or inpermutations which may or may not be specifically described in theillustrative embodiments listed herein. Further, the apparatus 900presented herein may be used in any desired environment. Thus FIG. 9(and the other FIGS.) should be deemed to include any and all possiblepermutations.

As shown, the apparatus 900 may further include a durable layer 822above an upper one of the magnetic shields 808. In other embodiments, adurable layer 824 may additionally and/or alternatively be positionedbelow a lower one of the magnetic shields 806. The durable layer(s) 822,824 may include a second refractory material. According to variousembodiments, the second refractory material in such layer(s) may be thesame as, or different than, the refractory material of the electricallyconductive layer between the shields as described above. In otherembodiments, the durable layer(s) 822, 824 may include a ferromagneticlayer of any suitable material, such as 45/55 NiFe. Thus, the durablelayer(s) 822, 824 may provide a wear support structure, which desirablyallows for an improved resistance to wear experienced on a media facingside of the sensor 802.

Moreover, although an electrically insulating separation layer 820 isshown in the present embodiment, e.g., to separate the durable layer 822from the shield 808, in some embodiments, the insulating layer 820 maybe omitted from the apparatus 900. Furthermore, the separation layer maybe electrically connected to shield 808 or other structure, such as asubstrate or closure, or voltage or current source.

Note that while much of the present description is presented in terms ofa data transducer, the teachings herein may be applied to createelectronic lapping guides (ELGs), such as TMR ELGs. In one embodiment,the ELG is unconventionally formed with shields, and with a TMRstructure that may be otherwise conventional, but modified as taughtherein. This provides enhanced immunity to shunting caused by scratchingduring lapping, which was previously not possible due to smearing of theshield material during lapping.

Although the embodiments of FIGS. 8A and 9 illustrate a single sensor802, according to various other embodiments, an apparatus may include anarray of the sensors sharing a common media-facing surface. Depending onthe desired embodiment, the array of sensors may include any of thedesigns, e.g., materials, layer combinations, etc., described above.

Moreover, for embodiments including an array of the sensors sharing acommon media-facing surface, the sensors may include any of thosedescribed herein, e.g., data readers, data writers, servo readers, etc.However, according to an exemplary embodiment, which is in no wayintended to limit the invention, an array of sensors sharing a commonmedia-facing surface may include only readers. In other words, nowriters would be present on the common media-facing surface of the arrayof sensors. For example, there may be no writers on the module at all,e.g., see 254 of FIGS. 3 and 252, 256 of FIG. 4.

FIG. 10 depicts an apparatus 1000 that is a variation of the embodimentof FIG. 9, in accordance with one embodiment. As an option, the presentapparatus 1000 may be implemented in conjunction with features from anyother embodiment listed herein, such as those described with referenceto the other FIGS. Of course, however, such apparatus 1000 and otherspresented herein may be used in various applications and/or inpermutations which may or may not be specifically described in theillustrative embodiments listed herein. Further, the apparatus 1000presented herein may be used in any desired environment. Thus FIG. 10(and the other FIGS.) should be deemed to include any and all possiblepermutations.

In other embodiments, an electrically conductive layer of at least oneof the gaps 810, 812 and/or durable layers 822, 824 may have a modifiedregion 834 at a media facing side thereof, e.g., such that the modifiedregion 834 is at least one of nonconductive (e.g., electricallyinsulating) and mechanically hardened, where a mechanically hardenedmodified region is physically harder and/or less ductile than theunmodified region of the layer. Thus, the nonconductive modified region834 is preferably able to prevent shorting caused by a magnetic mediumcoming into contact with the media facing side of the sensor stack whilethe magnetic medium is being passed thereover.

In one embodiment, the modified region may be an oxidized portion of theelectrically conductive layer. In another embodiment, the modifiedregion may be otherwise reacted by methods known in the art to altersurface characteristics such as by introduction of defects, whichgenerally have less shorting propensity. The process of forming themodified region may include applying a surface treatment to the mediafacing side of the sensor 802, thereby preferably affecting theproperties thereof. Thus, according to an exemplary embodiment, theelectrically conductive layer may include aluminum, while the modifiedregion includes aluminum oxide, e.g., crystalline aluminum oxide.Moreover, according to another illustrative embodiment, the electricallyconductive layer may include magnesium or a magnesium aluminum alloy,while the modified region may include crystalline magnesium oxide.

Such oxide portions may be formed by depositing or otherwise promotingthe formation of the oxide portion. In one example, the portion may beoxidized, followed by ion bombardment to promote conversion tocrystalline form.

According to exemplary embodiments, a modified region may be formed byimplementing various embodiments described in U.S. patent applicationSer. No. 13/624,466, filed on Sep. 21, 2012 and U.S. patent applicationSer. No. 13/624,484, filed on Sep. 21, 2012, which are hereinincorporated by reference.

In other embodiments, the modified region may be formed by performing asurface etching processes and/or milling processes. The process maynon-selectively remove non-gap metals that have an equal or lowerremoval rate than a refractory metal layer of the gap 810, 812.

It follows that such etching and/or milling processes may have an aboutequal or lower removal rate for one or more of the gaps 810, 812 thatmay include a refractory material therein. Moreover, these processes mayadditionally have a lower removal rate for the insulation gap betweenhard bias magnets and TMR stack and shields.

In some embodiments the hard bias magnets, typically comprised ofcobalt, platinum and chrome, etch at a rate equal to or greater than theother metals in the transducer structure.

By including at least one electrically conductive layer having arefractory material, the sensor 802 as described herein gains lowresistivity, low plasticity, low ductility, and high overall wearcharacteristics. It follows that by implementing such refractorymaterials as described above, the various embodiments of the presentinvention are able to successfully implement TMR sensors in contactrecording environments.

It will be clear that the various features of the foregoing systemsand/or methodologies may be combined in any way, creating a plurality ofcombinations from the descriptions presented above.

It will be further appreciated that embodiments of the present inventionmay be provided in the form of a service deployed on behalf of acustomer.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Thus, the breadth and scope of an embodiment of the presentinvention should not be limited by any of the above-described exemplaryembodiments, but should be defined only in accordance with the followingclaims and their equivalents.

What is claimed is:
 1. An apparatus, comprising: an array of sensorssharing a common media-facing surface, each sensor having an activetunnel magnetoresistive region, magnetic shields flanking the tunnelmagnetoresistive region, and gaps between the active tunnelmagnetoresistive region and the magnetic shields, wherein the activetunnel magnetoresistive region includes a free layer, a tunnel barrierlayer and a reference layer, wherein at least one of the gaps includesan electrically conductive layer having a refractory material.
 2. Anapparatus as recited in claim 1, wherein the array of sensors includesat least eight sensors in a single magnetic head.
 3. An apparatus asrecited in claim 1, wherein no writers are present on the commonmedia-facing surface.
 4. An apparatus as recited in claim 1, wherein therefractory material includes a metal selected from a group consisting oftungsten, titanium-tungsten, tungsten carbide, rhodium, ruthenium andiridium, and alloys thereof.
 5. An apparatus as recited in claim 1,wherein the sensor is an electronic lapping guide.
 6. An apparatus asrecited in claim 1, wherein the refractory material is selected from agroup consisting of conductive oxide, a conductive nitride and aconductive carbide.
 7. An apparatus as recited in claim 1, furthercomprising a seed layer disposed between the refractory material and asurface underlying the refractory material.
 8. An apparatus as recitedin claim 1, further comprising a layer of a second refractory materialabove an upper one of the magnetic shields and/or below a lower one ofthe magnetic shields.
 9. An apparatus as recited in claim 1, whereineach sensor further includes a ferromagnetic layer above an upper one ofthe shields and/or below a lower one of the shields.
 10. An apparatus asrecited in claim 1, further comprising: a drive mechanism for passing amagnetic medium over the sensor; and a controller electrically coupledto the sensor.
 11. An apparatus, comprising: a sensor having an activetunnel magnetoresistive region, magnetic shields flanking the tunnelmagnetoresistive region, and gaps between the tunnel magnetoresistiveregion and the magnetic shields, wherein the active tunnelmagnetoresistive region includes a free layer, a tunnel barrier layerand a reference layer, wherein at least one of the gaps includes anelectrically conductive layer having a modified region at a media facingside thereof, the modified region being at least one of nonconductiveand mechanically hardened.
 12. An apparatus, comprising an array ofsensors, each of the sensors being as recited in claim 11, the sensorssharing a common media-facing surface.
 13. An apparatus as recited inclaim 12, wherein no writers are present on the common media-facingsurface.
 14. An apparatus as recited in claim 13, wherein the modifiedregion is an oxidized portion of the electrically conductive layer. 15.An apparatus as recited in claim 11, wherein the modified region is anoxidized portion of the electrically conductive layer.
 16. An apparatusas recited in claim 11, wherein the electrically conductive layerincludes aluminum, wherein the modified region includes aluminum oxide.17. An apparatus as recited in claim 11, further comprising a layer ofrefractory material above an upper one of the magnetic shields and/orbelow a lower one of the magnetic shields.
 18. An apparatus as recitedin claim 17, wherein the refractory material includes a materialselected from a group consisting of tungsten, titanium-tungsten,tungsten carbide, rhodium, ruthenium, iridium, a conductive oxide, aconductive nitride, a conductive carbide, and non-annealed sendust. 19.An apparatus as recited in claim 11, further comprising a ferromagneticlayer above an upper one of the magnetic shields and/or below a lowerone of the magnetic shields.
 20. An apparatus as recited in claim 11,further comprising: a drive mechanism for passing a magnetic medium overthe sensor; and a controller electrically coupled to the sensor.